Microsoft is facing a fine of as much as $1 billion after European regulators said it failed to give customers a choice of Web browsers.

The European Union’s antitrust watchdog is expected to hit the Redmond, Wash., company with a fresh fine after finding that it broke the terms of an earlier order. Microsoft was told three years ago that it had to give users an option other than its own Internet Explorer browser.

In July, the European Commission said in a formal complaint that the company reneged on its promise. The commission has the right to charge up to 10 percent of Microsoft’s annual revenue, or nearly $7 billion, for breaking the agreement.

However, most analysts believe the fine will be lower. A source familiar with the EC’s thinking said the company will be fined “in the high hundreds of millions of dollars,” or as much as $1 billion.

The money isn’t an issue for Microsoft, which has a $60 billion-plus cash hoard. But it is an unwelcome reminder of that the regulatory woes that have plagued the once-dominant software giant.

“This is a reminder from the lost decade at Microsoft,” said BGC Partners analyst Colin Gillis. “For the last 10 years, there have been regulators in their office every day, scrutinizing every move. The pace of innovation was slow.”

Microsoft has a few weeks to respond to the charges, which it has blamed on a technical glitch with one of its software updates. The company also apologized.

Microsoft didn’t offer a screen where users could choose between browsers in Windows 7 between February 2011 and July of this year.

The commission has already socked Microsoft with about $1.3 billion in fines for failing to comply with another EU order.

An EC spokesman said it was too early to speculate on the fine as the EC sent its formal objection to Microsoft on Oct. 24.

“Microsoft now has the opportunity to provide its comments and exercise its rights of defense before the commission reaches a decision,” the spokesman said.

A Microsoft spokesman said, “Although this was the result of a technical error, we take responsibility for what happened, and we have taken steps to strengthen our internal procedures to help ensure something like this cannot happen again.”